1. Feidl of the Invention
The present invention relates to an optical record medium such as an optical card having a data record region in which a number of file data are record or to be recorded and a directory record region in which a number of directories for managing the file data recorded in the data record region is recorded.
2. Description of the Related Art
Heretofore, in order to manage a large amount of file data recorded on record medium such floppy disk and magnetic hard disk, there is used a directory. On a record medium there are provided a data record region and a directory record region, and the file data is recorded in the data record region and the directory is recorded in the directory record region. The directory is used as an index of file data and contains various management data such as file name, file size, a track address denoting a track on which the relevant file data has been recorded, and date and time on and at which the relevant file data and directory are recorded on the optical disk. When new data file is formed, a new directory is prepared. Further, when a file name is to be changed, a current file name recorded in a corresponding portion of a directory is rewritten into a new file name in case of using an erasable record medium.
However, in case of using an non-erasable type or write-once type optical card as the record medium, it is impossible to rewrite contents of the directory, so that the file name could not be changed directly. In Japanese Patent Publications Kokai Sho 63-69072 and 63-91888, there are proposed a method of erasing the directory logically. In the known method, there is provided an erase flag area in the directory and and when a bit 1 is recorded in the erase flag section, the directory is erased logically.
In the above mentioned known method of erasing the directory, when a file name is to be changed, at first file data denoted by the relevant file name is logically erased by providing the erase flag of "1" bit. Then, the relevant file data is recorded on a new information track in the data record region and a new directory having a new file name and a new track address is recorded in the directory region. In this manner, in the known optical card, the change of the file name requires a cumbersome operation and the data record region could not be utilized efficiently. That is to say, when the file name is changed three times, the same file data has to be recorded on three different tracks in the data record region.